How Xeriscaping Works

Xeriscaping is the newest tool in water management—coined in the American southwest, the term describes an innovative and creative means of conserving water through the landscape.

Because an estimated 50 percent of water consumption in the average single-family home is used outdoors, xeriscaping offers an ideal way to minimize water waste while maintaining the beautiful landscapes of our island. Outdoor water use in a xeriscape can save anywhere from 30 to 80 percent in water consumption. This means comparable savings in water and sewer charges, as well.

Xeriscaping is based on seven fundamental principles that serve as guidelines on how to plan, plant, and maintain a garden that takes advantage of natural climate conditions to make efficient use of irrigation. Although you may never convert your entire yard to a xeriscape, incorporating some of these principles may help it look beautiful and be more water efficient.

Seven Principles of Xeriscaping

1. A good xeriscape garden starts with good planning and design.

Planning allows you to install your landscape in phases, which minimizes initial expenses.

2. Limit and separate turf areas.

Grassed areas frequently require the greatest amount of watering. Turf is best separated from planting of trees, shrubs, ground covers, and flowering plants, so that it may be irrigated separately. Replace turf with other, less water-demanding materials such as ground covers, low water-demanding plants or mulches.

3. A well-planned sprinkler system can save water.

For efficient water use, group garden plants according to similar water needs. Turf areas are best watered with sprinklers. Trees, shrubs, garden flowers and ground covers can be watered efficiently with low volume drip, spray or bubbler emitters. Moisture sensors—devices that shut down the irrigation system when the ground is wet or on a rainy day—also help reduce water waste.

4. Soil improvement allows for better absorption of water and improved water-holding capacity.

Coupled with grading, soils and soil amendments that have organic matter—which provide beneficial nutrients to plants—will encourage whatever you plant to take root and flourish. Just remember that grading and soil improvements should be done prior to the installation of irrigation systems.

6. "Less-thirsty" plants improve your garden in more ways than one.

There are many attractive less-thirsty garden species available for use in the tropical xeriscape, including numerous popular flowering trees, shrubs and vines, and turf grasses, which require less watering than others. Ideally, native plants that thrive on natural rainfall do best in a xeriscape. There are many native Hawaiian plants that are less thirsty.

Because of their design, xeriscapes can help reduce maintenance costs. Pruning, weeding, proper fertilization, pest control, and irrigation system adjustments further water savings. Always water according to plant needs.

Xeriscaping also encourages the "zoning of landscapes," which means clustering your turf, ground cover, shrubs, plants and trees according to their water need—and according to how natural weather conditions affect each area of the landscape. These "microclimates" are affected by moisture, sun, shade, air movement, and heat.

For example, reflected light from structures facing the area of most sun creates high temperatures and increases the loss of water from nearby plantings. Shade trees and ground covers strategically planted in these exposures reduce temperatures in the warm, dry season, yet allow sunlight to enter during the months of high rainfall.

Similarly, water-loving plants can be grown in the microclimate zone of the landscape where irrigation and other water run-off is captured in drainage swales—again reducing the need for heavy watering. All of these microclimates utilize the Seven Principles of Xeriscaping.

Visit the Halawa Xeriscape Garden in Halawa Valley, just outside Honolulu. Free tours are offered by appointment. Self-guided tours and visits to the garden are available on Wednesdays and Saturdays from 9 a.m. until 3 p.m.